Such a rotary pump is known from GB-A-2,118,247 and is used in particular as a power steering pump for vehicles. In such an application the rotary pump is free from any other hydraulic system. The known rotary pump is satisfactory in such applications. The end plate is fitted with some play between an end face and the rotor. This play means that the end plate can be pressed in the optimum way against the rotor by fluid, in order in this way to eliminate leakage losses of the pump and increase the pump performance. Some leakage loss can occur between the end face and the end plate through this play.
If the known rotary pump were to be used in more complex hydraulic systems, in which several hydraulic lines are fitted close together, leakage loss of the pump or of the other hydraulic systems through the gap between the end face and the end plate would be undesirable. Thus, for layout reasons, if the rotary pump is used in a continuously variable transmission, the supply and/or discharge line of, for example, the coupling transformer or of the hydraulic cylinders of the pulleys used in it can be fitted along the rotor/drive shaft connection. The coupling transformer and/or the hydraulic cylinders could in this case gradually run dry or even be sucked dry by the pump through the gap between the end plate and the end face. This makes the transmission and the pump difficult to start up, and air can enter the system. The pressure for the coupling transformer might also not be high enough for reaching lock-up. In the case of such leakage losses a pump with a greater capacity might also be necessary.